Karen Nakamura: February 2010 Archives

My latest acquisition is a beautiful old Garelli moped. I'm still ambivalent as to whether this will be EV converted. For now, here are some pics from the seller.

The seller called it a 1972 Garelli Bonanza, but I'm pretty sure it's a 1976 Garelli Eureka Flex instead. Here are some links to other Garelli Eurekas:

• http://www.mopedarmy.com/photos/brand/18/1844/
• http://www.flickr.com/photos/63216488@N00/3404162837/

MopedArmy.org has the Clymer's repair manual for the Garelli on their website, but it's individual JPG files and I found it difficult to use so I collated them into a single PDF:

A recent find in an estate sale was this old Amprobe analog amp-volt-ohm meter. I believe it's an Amprobe RS300 but not entirely sure, since the RS300 apparently isn't supposed to have an ohmmeter on it.

My one has:

• Amps: 0-6; 15; 40; 100; 300
  
• Volts: 0-150; 300; 600
  
• Ohms 0-1K ohm
  

PDF manual: Amprobe-RS7A.pdf

This isn't entirely useful as most of my circuits aren't AC, the voltage range is too high, and it's missing the attachment for the ohmmeter which isn't switchable range and not that useful either.

But it is bakelite and looks nice! :P

I had hooked up one of my larger SLA batteries to a winch to move some logs around. I thought that the 30 amp PowerPole connectors on the battery leads were maybe a bit undersized for the winch, but was lazy and went with them anyway.

I originally thought one of the PowerPoles wasn't properly seated and it melted down. That's perhaps one of the problems with the small PowerPoles, there isn't a clean "click" confirmation of seating.

Closer examination of one of the melted PowerPoles showed however that the tongue that grips the connector had arcing on it; obviously it had shorted and overheated, causing a melting of the connector. Very strange.

Closer examination of the crimped connector showed that the connector itself was bent upwards. What I now think happened was that the main body of the plug was bent and not seated in the plastic case, and this caused the mating connector's plug to wedge itself between the tongue and the plug (instead of on top of the plug), causing sparking and overheating.

Me want a Honda Gyro Canopy. Perfect for commuting to work in harsh New England winters, along with your little puppy:

Unfortunately, very difficult to find in the USA and I'm not sure I want to go to the trouble of importing one from Japan just to convert it to EV.

Or maybe I can skip the whole EV conversion if I can find an elusive electric Daihatsu Hallo, whose "two 12V batteries, whose 75Ah capacity gave it a 30km range at a speed of 30km/h."

Well, my favorite discrete component of the week has to be the lowly LM317 voltage/current regulator. As one of my previous posts showed, I'm using it to current regulate some high power LEDs and I also use it as a voltage regulator.

Here's the quick and easy way to wire up an LM317 as a voltage regulator:

where the values of R2 and R1 are calculated as follows to give Vout:

R2 is usually set to 240 ohms and you can ignore Iadj to a point. Rearranging the equation gives you:

So if you want a 5 volt output, then R2 = 720 ohm (and R1 = 240 ohm). The TO-220 form factor of the LM317 that I'm using can provide up to 1.5 amps of output current and can be paralleled if I need more.

Late update: or you can just use an online calculator: http://www.jlab.org/~hansknec/index.html